Bearingless Gimbaled Rotor Hubs and Swashplates

ABSTRACT

A gimbal joint may employ a plurality of wear sleeves, each disposed between a pin or pin receptive bore of a first structure and a corresponding bore or pin of a second structure and between another pin or bore of the second structure and a corresponding bore or pin of a third structure. Each of these structures may be adapted to rotate in a single plane, with one structure adapted to also tilt about a first axis, and one other structure adapted to tilt about a second axis. Each integral flanged wear sleeve may comprise a right circular hollow cylindrical body portion, which may be interiorly sized to be retained on one of the pins and externally sized to be retained in one of the pin receptive bores, and a flange portion may radiate from one end of the cylindrical body portion.

CROSS-REFERENCE TO RELATED APPLICATION

This is a divisional of, and claims benefit of, U.S. patent applicationSer. No. 16/004,689, also entitled Bearingless Gimbaled Rotor Hubs andSwashplates, filed Jun. 11, 2018, which is hereby incorporated herein byreference.

TECHNICAL FIELD

The present disclosure relates generally to rotorcraft, moreparticularly to rotorcraft rotor hubs, and specifically to bearinglessgimbaled rotor hubs and swashplates.

BACKGROUND

A rotorcraft (i.e. rotary-wing aircraft, such as helicopters andtiltrotor aircraft) may include one or more rotor systems. At least onerotor provides lift and propulsion forces. These rotors commonly havingtwo or more airfoil blades connected to a rotatable hub.

For example, in a helicopter main rotor system, or in a tiltrotoraircraft, the tilting rotor, may generate aerodynamic lift to supportthe weight of the rotorcraft in flight and thrust to counteractaerodynamic drag and move the rotorcraft in forward flight. In ahelicopter, a tail rotor system may generate thrust in the samedirection as the main rotor system's rotation to counter the torqueeffect created by the main rotor system.

Tiltrotor aircraft may operate in helicopter mode by tilting at least arotor portion of the craft's nacelles upright and in an airplane mode bytilting the nacelles forward. While in helicopter mode the aircraft mayperform vertical maneuverers, including vertical takeoff and landing, aswell as hover and sideward movement. Tiltrotor aircraft may generategreater forward speed in airplane mode than in helicopter mode because,in airplane mode, blades are oriented to generate greater thrustpropelling the aircraft forward (somewhat analogous to a propeller),

Designs of rotors and propellers for aircraft are often extremelycomplex. A large number of factors must be taken into account, includingflexure of the rotor under heavy loads and the required motions of therotor blades with respect to the drive mechanism. The advent of the tiltrotor aircraft has added performance requirements to the hub assembly,resulting from the more complex operation of the craft. The prop systemson a tiltrotor are very large by comparison with standard aircraft.Hence, considerations for proprotors, used as both propellers and rotorsin aircraft such as a tiltrotor aircraft, can be even more complex thanusual. For example, prior rotor hubs use elastomeric bearings ormetallic roller/ball bearings to allow for rotation (gimbaling) betweenparts while constraining shear loads. However, such prior bearings areexpensive and difficult to replace. For example, replacement of suchbearing typically require replacement of one or more surrounding parts.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

The present invention is directed to systems and methods which provide agimbal particularly well suited for use in an aircraft rotor hub,swashplate, or the like. In accordance therewith, a gimbal joint mayemploy a plurality of wear sleeves, each disposed between a pin or pinreceptive bore of a first structure and a corresponding bore or pin of asecond structure and between another pin or bore of the second structureand a corresponding bore or pin of a third structure. Each of thesestructures may be adapted to rotate in a single plane, with onestructure adapted to also tilt about a first axis, and one otherstructure adapted to tilt about a second axis. Each integral flangedwear sleeve may comprise a right circular hollow cylindrical bodyportion, which may be interiorly sized to be retained on one of the pinsand externally sized to be retained in one of the pin receptive bores,and a flange portion may radiate from one end of the cylindrical bodyportion.

Various gimbal embodiments may be adapted to be secured or linked to aproprotor yoke, which is configured to radially mount a plurality ofproprotors, or the like and that defines a central driveshaft or mastopening. The gimbal may include an integral universal joint trunnionthat has an annular body portion defining a central driveshaft or mastopening, aligned with the proprotor yoke central driveshaft or mastopening, and a plurality of drive pin portions extending from theannular body portion.

A pair of pillow blocks may be secured to the proprotor yoke, with eachpillow block defining a trunnion pin receptive bore. A drive couplingmay define a splined central driveshaft or mast coupling bore,configured to be mated with a rotor driveshaft or mast end, and opposingtrunnion pin receptive bores.

One of a plurality of integral flanged wear sleeves may be disposed ineach of the pillow block trunnion pin receptive bores and each of thedrive coupling trunnion pin receptive bores, over a respective trunniondrive pin. This rotatably retains the respective trunnion drive pin withrespect to the respective pillow block trunnion pin receptive bore ordrive coupling trunnion pin receptive bore. Each of the integral flangedwear sleeves has a right circular hollow cylindrical body portion,interiorly sized to be retained on one of the trunnion drive pinportions of the trunnion, and externally sized to be rotatably retainedin one of the pillow block trunnion pin receptive bores and/or one ofthe drive coupling trunnion pin receptive bores. Each of the integralflanged wear sleeves also includes a flange portion, radiating from anouter end of the cylindrical body portion. The flange portion has adiameter larger than a diameter of the pillow block trunnion pinreceptive bores and the drive coupling trunnion pin receptive bores, soas to bear on a face of a respective pillow block or drive coupling. Alow friction coating or lining is disposed on at least an outer surfaceof the body portion. The low friction coating or lining may also, oralternatively, be disposed on at least an inner face of the flangeportion of each wear sleeve.

Each drive pin portion of the integral trunnion may have a (threaded)longitudinal bore, and a (threaded) fastener may be secured in (threadedand tightened into) each trunnion drive pin longitudinal bore. A head ofthe fastener may bear on, and tension against, the respective wearsleeve flange, replaceably retaining the respective wear sleeve on therespective trunnion drive pin and replaceably retaining the flanged wearsleeve and trunnion in place.

Hence, a process for gimbaling a rotor hub, swashplate, or the like,may, for example include disposing integral flanged wear sleeves betweenpins or pin receptive bores of a first structure and corresponding pinreceptive bores or pins of a second structure. This first structure maybe adapted to, for example rotate in a single plane and the secondstructure may, for example, be adapted to rotate in the single plane andtilt relative to the single plane about a first axis parallel to thesingle plane. Other integral flanged wear sleeves may be disposedbetween other pins or pin receptive bores of the second structure andcorresponding pin receptive bores or pins of a third structure. Thisthird structure may be adapted to rotate in the single plane and tiltrelative to the single plane about a second axis parallel to the singleplane and perpendicular to the first axis.

In accordance with the foregoing, in a rotor hub implementation, or thelike, the first structure, for example, may be splined to a mast ordriveshaft of a proprotor aircraft, and proprotors of the aircraft may,by way of example, be mounted to the third structure, such as aproprotor yoke.

Additionally, or alternatively, in a swashplate implementation, or thelike, another first structure may be splined to a mast or driveshaft ofa proprotor aircraft for movement along the mast or driveshaft,perpendicular to the single plane and another third structure may belinked to proprotors of the aircraft.

The foregoing has outlined rather broadly the features and technicaladvantages of the present invention in order that the detaileddescription of the invention that follows may be better understood.Additional features and advantages of the invention will be describedhereinafter which form the subject of the claims of the invention. Itshould be appreciated that the conception and specific embodimentdisclosed may be readily utilized as a basis for modifying or designingother structures for carrying out the same purposes of the presentinvention. It should also be realized that such equivalent constructionsdo not depart from the invention as set forth in the appended claims.The novel features which are believed to be characteristic of theinvention, both as to its organization and method of operation, togetherwith further objects and advantages will be better understood from thefollowing description when considered in connection with theaccompanying figures. It is to be expressly understood, however, thateach of the figures is provided for the purpose of illustration anddescription only and is not intended as a definition of the limits ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus described the invention in general terms, reference will nowbe made to the accompanying drawings, which are not necessarily drawn toscale and which are incorporated in and form part of the specificationand in which like numerals designate like parts, illustrate embodimentsof the present invention and together with the description, serve toexplain the principles of the invention. In the drawings:

FIG. 1 is perspective view of an unmanned tiltrotor aircraft, such asmay employ embodiments of the present systems and methods;

FIG. 2 is a diagrammatic perspective view of a portion of a rotor hubassembly of a rotorcraft such as the unmanned tiltrotor aircraft of FIG.1, showing a bearingless gimbaled rotor hub Hooke's joint, in accordancewith at least one embodiment of the present systems and methods;

FIG. 3 is a diagrammatic perspective view of a trunnion of thebearingless gimbaled rotor hub Hooke's joint 205 of FIG. 2, inaccordance with at least one embodiment of the present systems andmethods;

FIG. 4 is fragmented, generally cross-sectional diagrammatic side viewof the portion of the rotor hub assembly of FIG. 2 also showing thebearingless gimbaled rotor hub Hooke's joint, in accordance with atleast one embodiment of the present systems and methods;

FIG. 5 is another fragmented, generally cross-sectional diagrammaticside view of the portion of the rotor hub assembly of FIG. 2 alsoshowing the bearingless gimbaled rotor hub Hooke's joint, in accordancewith at least one embodiment of the present systems and methods;

FIG. 6 is fragmented, partially exploded diagrammatic perspective viewof another bearingless gimbaled Hooke's joint, according to at least oneother embodiment of the present systems and methods;

FIG. 7 is fragmented, partially exploded diagrammatic perspective viewof a further bearingless gimbaled Hooke's joint, according to at leastone further embodiment of the present systems and methods; and

FIG. 8 is a flowchart of an example process for gimbaling a rotor hub,according to at least one implementation of the present systems andmethods

While this specification provides several embodiments and illustrativedrawings, a person of ordinary skill in the art will recognize that thepresent specification is not limited only to the embodiments or drawingsdescribed. It should be understood that the drawings and detaileddescription are not intended to limit the specification to theparticular form disclosed, but, on the contrary, the intention is tocover all modifications, equivalents and alternatives falling within thespirit and scope of the claims. As used herein, the word “may” is meantto convey a permissive sense (i.e., meaning “having the potential to”),rather than a mandatory sense (i.e., meaning “must”). Similarly, thewords “include,” “including,” and “includes” mean “including, but notlimited to.”

DETAILED DESCRIPTION

The invention now will be described more fully hereinafter withreference to the accompanying drawings. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein. Rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art. Oneskilled in the art may be able to use the various embodiments of theinvention.

The present systems and methods relate generally to rotorcraft, moreparticularly to rotorcraft rotor hubs, and specifically to bearinglessgimbaled rotor hubs and swashplates. In accordance with embodiments ofthe present systems and methods, an aircraft gimbal includes a universaljoint trunnion having an annular body with a plurality of drive pinsextending therefrom. A pair of pillow blocks secured to a proprotor yokeeach define a trunnion pin receptive bore. A drive coupling defines asplined central driveshaft or mast coupling bore and opposing trunnionpin receptive bores. A flanged wear sleeves is disposed in each of thepin receptive bores, over a respective trunnion drive pin, rotatablyretaining the respective trunnion drive pin with respect to therespective trunnion pin receptive bore. Each integral flanged wearsleeve has a hollow cylindrical body sized to be retained on one of thetrunnion drive pin and to be rotatably retained in one of the trunnionpin receptive bores. A low friction coating or lining is disposed on atleast an outer surface of the body.

The present, bearingless gimbaled rotor hubs and swashplates avoid theuse of expensive elastomeric or metallic roller/ball bearings, whileallowing the rotorcraft to achieve the rotor flapping, teetering, or thelike. Embodiments of the present systems and methods employ a wearsleeve that is lined/coated with a low friction material, such aspolytetrafluoroethylene (PTFE or Teflon®) instead. Employing embodimentsof the present systems and methods make the rotorcraft hub package(and/or the hub and swashplate package) smaller. In accordance withembodiments of the present systems and methods, the wear sleeve attachedin an easily removable fashion to be replaced as necessary, without theneed to remove and/or replace surrounding parts, proving cost and timesavings over expensive traditional elastomeric or metallic roller/ballbearings.

FIG. 1 is perspective view of an unmanned tiltrotor aircraft 100, suchas may employ embodiments of the present systems and methods. Rotorcraft100 features rotor systems 105 and 110, blades 115, a fuselage 120,landing gear 125, and wing 130. Rotor systems 105 and 110 may rotateblades 115. Rotor systems 105 and 110 may include a control system forselectively controlling pitch of each blade 115 in order to selectivelycontrol direction, thrust, and lift of rotorcraft 100. In the example ofFIG. 1, rotorcraft 100 is a tiltrotor aircraft, and rotor systems 105and 110 take the form of rotatable nacelles. In this example, theposition of (at least the rotor portion and driveshafts/masts of)nacelles 105 and 110, as well as the pitch of rotor blades 115 (as wellas tip portions 135 and 140 of wing 130), can be selectively andseparately controlled in order to selectively control direction, thrust,and lift of tiltrotor aircraft 100. Fuselage 120, the main body ofrotorcraft 100, may be coupled to rotor systems 105 and 110 (e.g., viawing 130) such that rotor systems 105 and 110 and blades 115 may movefuselage 120 through the air. Landing gear 125 supports rotorcraft 100when rotorcraft 100 is landing and/or when rotorcraft 100 is at rest onthe ground. Various embodiments of the present systems and methodsrelating to rotor systems described herein may apply to rotor systems105 and 110 and/or other rotor systems, such as non-tilting rotor,helicopter rotor systems, aircraft other than rotorcraft, such asairplanes and unmanned (drone) aircraft, or the like.

In the example of FIG. 1, tiltrotor aircraft 100 may operate in ahelicopter mode by tilting (at least the rotor portion anddriveshafts/masts of) nacelles 105 and 110 upright (including, in someembodiments tip portions 135 and 140 of wing 130), as shown with respectto nacelle 105 (and wing tip 135). Tiltrotor aircraft 100 may operate inan airplane mode by tilting the (rotor portion and driveshafts/masts ofthe) nacelles (and in some embodiments tip portions 135 and 140 of wing130) forward, as nacelle 110 (and wing tip 140) is shown. Tiltrotoraircraft 100 may operate in a transition flight or conversion mode bytilting the (rotor portion and driveshafts/masts of) nacelles (andwingtips) between the upright and forward orientations. Tiltrotoraircraft 100 may generate greater forward speed in airplane mode than inhelicopter mode because, in airplane mode, blades 115 are oriented togenerate greater thrust propelling the aircraft forward (somewhatanalogous to a propeller). While in helicopter mode tiltrotor aircraft100 can take off and land vertically, hover and fly sideward.

As noted, designs of rotors and propellers for aircraft are often(extremely) complex. A large number of factors must be taken intoaccount, including flexure of the rotor under heavy loads and therequired motions of the rotorblades with respect to the drive mechanism.The considerations for proprotors, used as both propellers and rotors inaircraft such as tiltrotor aircraft 100, can be more complex than usual.Gimbaled rotors may be used in such aircraft. In a gimbaled rotor,joints must be provided between the driveshaft/mast that carries torquefrom the engine and the yoke that drives the blades, giving rise to arelatively complex hub assemblies subject to considerable forces in suchjoints.

In accordance with embodiments of the present systems and methods, agimbal joint may employ a first set of integral flanged wear sleeves.Each of these integral flanged wear sleeves may be disposed between apin or pin receptive bore of a first structure and a correspondingrespective pin receptive bore or pin of a second structure. The firstsuch structure may be adapted to rotate in a single plane and the secondsuch structure may be adapted to rotate in the single plane and tiltrelative to the single plane, about a first axis parallel to the singleplane. A second set of the integral flanged wear sleeves may each bedisposed between another pin or pin receptive bore of the secondstructure and a corresponding respective pin receptive bore or pin of athird structure. This third structure may be adapted to rotate in thesingle plane and tilt relative to the single plane, about a second axisparallel to the single plane and generally perpendicular to the firstaxis.

The present systems and methods are described herein with reference to arotorcraft rotor (proprotor) hub. However, various embodiments of thepresent systems and methods are applicable to not only aircraft rotor orpropeller hub assemblies, but also to swashplate assemblies used tocontrol rotor or propeller pitch. To wit, FIG. 2 is a diagrammaticperspective view of a portion of a rotor hub assembly 200 of arotorcraft such as unmanned tiltrotor aircraft 100 of FIG. 1, showingbearingless gimbaled rotor hub Hooke's or “universal” joint 205, inaccordance with at least one embodiment of the present systems andmethods. FIG. 3 is a diagrammatic perspective view of trunnion 210 ofbearingless gimbaled rotor hub Hooke's or “universal” joint 205 of FIG.2, in accordance with at least one embodiment of the present systems andmethods. FIG. 4 is fragmented, generally cross-sectional diagrammaticside view of the portion of rotor hub assembly 200 of FIG. 2 alsoshowing bearingless gimbaled rotor hub Hooke's or universal joint 205,in accordance with at least one embodiment of the present systems andmethods. FIG. 5 is another fragmented, generally cross-sectionaldiagrammatic side view of the portion of rotor hub assembly 200 of FIG.2 also showing the bearingless gimbaled rotor hub Hooke's or universaljoint, in accordance with at least one embodiment of the present systemsand methods.

Rotor hub gimbal 205 includes a “first structure,” such as drivecoupling 215, which in accordance with such embodiments, adapted torotate in a single plane, such as by virtue of being splined onto adriveshaft/mast of the aircraft. To wit, drive coupling 215 definessplined central driveshaft/mast coupling bore 220 configured to matewith a rotor driveshaft/mast end. Drive coupling 215 also definesopposing trunnion pin receptive bores 505 (best seen in FIG. 5).

Rotor hub gimbal embodiment 205 also includes a “second structure,” suchas integral universal joint trunnion 210, which may, in some embodimentsand implementations be referred to as a “universal joint cross.”Trunnion 210, is, in accordance with such embodiments, adapted to rotatein the aforementioned single plane and tilt relative to the singleplane, about a first axis parallel to the single plane, such as byvirtue of being rotatably pined to drive coupling 215. As may be bestseen in FIG. 3, integral trunnion 210 may comprise generally cylindricalannular body portion 225, which in some embodiments may be torus-shaped(i.e. doughnut-shaped), defining central driveshaft/mast opening 305.Generally cylindrical drive pin portions 310 extend radially fromannular body portion 225. Each drive pin portion 310 of integraluniversal joint trunnion 210 may include a threaded longitudinal bore315.

Returning to FIG. 2, in the illustrated embodiment, a pair of pillowblocks 230 and 235 are secured to a “third structure,” such as proprotoryoke 240. In accordance with such embodiments, proprotor yoke 240 isadapted to rotate in the aforementioned single plane and tilt relativeto the single plane, about a second axis parallel to the single planeand generally perpendicular to the first axis about which the secondstructure trunnion 210 tilts.

In the illustrated embodiment of FIGS. 2 through 5, each pillow blockdefines a trunnion pin receptive bore 405 or 410 (best seen in FIG. 4).However, in other embodiments the pin receptive bores may be defined bythe third structure proprotor yoke itself. Each illustrated pillow blockmay, as illustrated, comprise two halves, halves 245 and 250 making uppillow block 230 and halves 255 and 260 making up pillow block 235. Eachof pillow block halves 245, 250, 255 and 260, is configured to besecured to proprotor yoke 240, such as by a bolt deployed in recesses245 a and 255 a (and corresponding hidden recesses) of pillow blockhalves 245 and 255. Pillow block halves 245 and 250 mate to define pinreceptive bore 405, while pillow block halves 255 and 260 mate to definepin receptive bore 410, in the illustrated embodiment. The horizontalsplit between the pillow block halves allows control an amount ofcompression on the wear sleeve. Shims may be employed between the pillowblock halves to control that compression. However, each of pillow blocks230 and 235 may be a single piece, defining pin receptive bores 405 and410.

Integral flanged wear sleeves 265, which may be identical, are disposedin each of pillow block trunnion pin receptive bores 405 and 410, andeach of drive coupling trunnion pin receptive bores 505, over respectivetrunnion drive pins 310. Integral flanged wear sleeves 265 rotatablyretain respective trunnion drive pin 310 with respect to respectivepillow block trunnion pin receptive bore 405 or 410, or respective drivecoupling trunnion pin receptive bore 505. Each integral flanged wearsleeve 265 comprises right circular hollow cylindrical body portion 415,which may be interiorly sized to be retained on one of trunnion drivepin portions 310 of universal joint trunnion 210 and externally sized tobe rotatably retained in pillow block trunnion pin receptive bores 405and 410 and drive coupling trunnion pin receptive bores 505. Flangeportion 270, radiating from an “outer” end of cylindrical body portion415, has a diameter larger than a diameter of pillow block trunnion pinreceptive bores 405, 410 and drive coupling trunnion pin receptive bores505, bearing on a face (275 shown) of pillow blocks 230, 235 or a face(280 shown) of drive coupling. A low friction coating or lining, such asPTFE, or the like, is disposed on at least outer surface 420 of bodyportion 415 of each integral flanged wear sleeve 265 and may be disposedon inner face 425 of flanges 270. In some embodiments, the low frictioncoating or lining may, additionally or alternatively, be disposed on atleast inner cylindrical surface 430 of each wear sleeve 265.

Each structure pin may also define a longitudinal bore, in suchembodiments the gimbal joint may employ a fastener secured in each suchlongitudinal bore, bearing on, and tensioned against, the respectivewear sleeve flange to replaceably retain the respective wear sleeve onthe respective pin and in the respective pin receptive bore. In suchembodiments, the right circular hollow cylindrical body portion isinteriorly sized to be retained on one of the pins and externally sizedto be rotatably retained in one of the pin receptive bores. To wit, afastener, such as illustrated bolt 285, may be secured in (e.g. threadedand tightened into) each trunnion drive pin longitudinal (threaded) bore315, so as to bear on and tension against the respective wear sleeveflange 270, thereby replaceably retaining respective wear sleeve 265 onrespective trunnion drive pin 310 and replaceably retaining flanged wearsleeve 265 and trunnion 210 in place. Thereby, gimbaled rotor hub 200 isconfigured to enable removal of one fastener 285 to allow removal andreplacement of a respective wear sleeve 265, one at a time, withoutremoval of rotor hub gimbal 205 or any other components thereof.Further, a low friction coating or lining, may, such as described above,be disposed on an outer surface of the body portion and on an inner faceof the flange portion of each wear sleeve, in such embodiments.Alternatively, right circular hollow cylindrical body portion 415 ofeach wear sleeve 265 may be interiorly sized to be rotatably retained onone of the pins and externally sized to be retained in one of the pinreceptive bores.

In accordance with the foregoing, a gimbaled rotor hub (200) may have aproprotor yoke (240), configured to radially mount a plurality ofproprotors and defining a central driveshaft/mast opening (290), with arotor hub gimbal 205 rotatably mounted on the proprotor yoke (240) andcoupled to a driveshaft/mast of the aircraft. To facilitate tilting ofthe gimbaled rotor hub (200) on the driveshaft/mast the proprotor yokecentral driveshaft/mast opening (290) is larger than the annular bodycentral driveshaft/mast opening (305), which is larger in diameter thanthe drive coupling splined opening (220), thereby allowing tilting ofproprotors secured to the proprotor yoke, for purposes such as rotorflapping or teetering.

FIG. 6 is fragmented, partially exploded diagrammatic perspective viewof other bearingless gimbaled Hooke's joint 600, according to at leastone other embodiment of the present systems and methods. Therein, a“first structure,” in this case integral trunnion 605, is, in accordancewith such embodiments, adapted to rotate in a single plane, such as byvirtue of being splined onto a driveshaft/mast of an aircraft. To thisend, trunnion 605 defines integral internally splined centraldriveshaft/mast coupling bore portion 610 configured to mate with arotor driveshaft/mast end. Trunnion 605 also defines opposing integraltrunnion pin portions 615.

Bearingless gimbaled Hooke's joint 600 also includes a “secondstructure,” such as integral coupling 620, which in accordance with suchembodiments, adapted to rotate in the aforementioned single plane, andtilt relative to the single plane, about a first axis parallel to thesingle plane, such as by virtue of being rotatably pined to trunnion605. As illustrated, coupling 620 may be “ring-shaped” and may defineintegral pin receptive bore portions 625 for rotatably pinning totrunnion 605, via trunnion pins 615. Coupling embodiment 620 alsodefines integral coupling pin portions 630.

“Third structures,” which in FIG. 6 are illustrated as pillow blocks 635and 640 are, in accordance with such embodiments, adapted to rotate inthe aforementioned single plane and tilt relative to the single plane,about a second axis parallel to the single plane and generallyperpendicular to the first axis about which second structure ringcoupling 620 tilts. Each pillow block 635 and 640 defines a coupling pinreceptive bore, 645 and 650, respectively. In various embodiments pillowblocks 635 and 640 may be secured to, or be an integral part of, aproprotor yoke, or the like, of the aircraft.

Integral flanged wear sleeves 655, similar to (or the same as) integralflanged wear sleeve 265, may be identical. Integral flanged wear sleeves655 are each adapted to be disposed in each of coupling ring pinreceptive bores 625, and each of pillow block pin receptive bores 645and 650, over respective trunnion drive pins 615, or coupling ring drivepins 630, respectively. Integral flanged wear sleeves 655 rotatablyretain respective trunnion drive pin 615 with respect to respectivecoupling ring pin receptive bore 625, or respective coupling ring drivepin 630 with respect to respective pillow block pin receptive bore 645or 650, coupling trunnion 605 to the third structure, such as aproprotor yoke of the aircraft.

Again, each integral flanged wear sleeve 655 comprises right circularhollow cylindrical body portion 660, which may be interiorly sized to beretained on one of trunnion or coupling drive pin portions 615 or 630and externally sized to be rotatably retained in coupling bore 625 orpillow block bore 645 or 650. Flange portion 665, radiates from an“outer” end of cylindrical body portion 660 and has a diameter largerthan a diameter of coupling or pillow block pin receptive bores 625, 645or 650, for bearing, at least in part on outer surface 670 of couplingring 620 or a face (675 shown) of pillow blocks 635 or 640. Again, a lowfriction coating or lining, such as PTFE, or the like, may be disposedon at least an outer surface of body portion 660 of each integralflanged wear sleeve 655 and may be disposed on inner face of flanges665. In some embodiments, the low friction coating or lining may,additionally or alternatively, be disposed on at least inner cylindricalsurface of each wear sleeve 655.

FIG. 7 is fragmented, partially exploded diagrammatic perspective viewof further bearingless gimbaled Hooke's joint 700, according to at leastone further embodiment of the present systems and methods. In accordancewith such embodiments, a “first structure,” such as illustrated integraltrunnion 705, is adapted to rotate in a single plane, such as for beingsplined onto a driveshaft/mast of an aircraft. To wit, trunnion 705defines integrally internally splined central driveshaft/mast couplingbore portion 710 configured to mate with a rotor driveshaft/mast end.Trunnion 705 also defines opposing integral 710 trunnion pin portions715.

Bearingless gimbaled Hooke's joint 700 also includes a “secondstructure,” illustrated integral ring coupling 720, which in accordancewith such embodiments, is adapted to rotate in the aforementioned singleplane, and tilt relative to the single plane, about a first axisparallel to the single plane, such as by being rotatably pined totrunnion 705. As illustrated, coupling 720 may be “ring-shaped” and maydefine integral pin receptive bore portions 725 for rotatably pinning totrunnion 705, via trunnion pins 715 and rotatably pinning to mountingblocks 730 and 735, via respective mounting pins (mounting block 730 pin740 shown).

Mounting block “third structures” 730 and 735 are adapted to rotate inthe aforementioned single plane and tilt relative to the single plane,about a second axis parallel to the single plane and generallyperpendicular to the first axis about which second structure ringcoupling 720 tilts, in accordance with such embodiments. Each mountingblock 730 and 735 defines the aforementioned mounting pin (mounting pin740 of mounting block 730 shown. In various embodiments mounting blocks730 and 735 may be secured to, or be an integral part of, a proprotoryoke, or the like, of the aircraft.

Integral flanged wear sleeves 745, similar to (or the same as) integralflanged wear sleeve 265 or 655, may be identical. Integral flanged wearsleeves 745 are each adapted to be disposed in each of coupling ring pinreceptive bores 725 over respective trunnion drive pins 715 or themounting pins (740). Integral flanged wear sleeves 745 rotatably retainrespective trunnion drive pin 715 or the respective mounting pin (740)with respect to the respective coupling ring pin receptive bore 725,coupling trunnion 705 to the third structure mounting blocks 730 and735, and thereby to a proprotor yoke of the aircraft, or the like.

Again, each integral flanged wear sleeve 745 comprises right circularhollow cylindrical body portion 750, which may be interiorly sized to beretained on one of trunnion or mounting block pin portions 715, 730 etc.and externally sized to be rotatably retained in coupling bores 725 ofcoupling ring 720. Flange portion 755, radiates from an “outer” end ofcylindrical body portion 750 and has a diameter larger than a diameterof coupling ring pin receptive bores 725, for bearing, at least in parton outer or inner surface 760 or 765 of coupling ring 720. Again, a lowfriction coating or lining, such as PTFE, or the like, may be disposedon at least an outer surface of body portion 750 of each integralflanged wear sleeve 745 and may be disposed on inner face of flanges755. In some embodiments, the low friction coating or lining may,additionally or alternatively, be disposed on at least inner cylindricalsurface of each wear sleeve 745.

Again, in each of embodiments 600 and 700, each structure pin may alsodefine a longitudinal bore 680 or 685 and 770 or 775, respectively. Insuch embodiments the gimbal joint may employ a fastener (not shown)passing through wear sleeve orifice 690 or 780 and secured in each suchlongitudinal bore, bearing on, and tensioned against, the respectivewear sleeve flange 665 or 755 to replaceably retain the respective wearsleeve 655 or 745 on the respective pin and in the respective pinreceptive bore.

A process for gimbaling a rotor hub, swashplate, or the like, may, forexample include disposing integral flanged wear sleeves between pins orpin receptive bores of a first structure and corresponding pin receptivebores or pins of a second structure. This first structure may be adaptedto, for example rotate in a single plane and the second structure may,for example, be adapted to rotate in the single plane and tilt relativeto the single plane about a first axis parallel to the single plane.Other integral flanged wear sleeves may be disposed between other pinsor pin receptive bores of the first structure and corresponding pinreceptive bores or pins of a third structure. This third structure maybe adapted to rotate in the single plane and tilt relative to the singleplane about a second axis parallel to the single plane and perpendicularto the first axis.

In accordance with such implementations, a rotor hub implementation, orthe like may call for the first structure to be splined to a mast ordriveshaft of a proprotor aircraft, and proprotors of the aircraft maybe mounted to the third structure, such as a proprotor yoke. To such anend, FIG. 8 flowcharts example process 800 for gimbaling a rotor hub,according to at least one implementation of the present systems andmethods. Therein, a pair of pillow blocks (230, 235) are mounted to aproprotor yoke (240, a “third structure”), at 805. Each pillow blockdefines a trunnion pin receptive bore (405, 410), and the proprotor yokedefines a central driveshaft/mast opening (290). Each of the pillowblocks may comprise two halves (245, 250, 255, 260), and mounting eachof the pillow blocks at 805 may be carried out by mating and securingeach half to the proprotor yoke, defining the respective pillow blockpin receptive bore.

At 810, a rotor hub gimbal annular universal joint trunnion (210, a“second” structure) defining a central driveshaft/mast opening (305),aligned with the proprotor yoke central driveshaft/mast opening (290),is disposed with radial drive pins (310) of the trunnion disposed in thetrunnion pin receptive bores (405, 410) of the pillow blocks (230, 235).Mounting each of the pillow blocks stacked one upon the other, at 805,may thereby capture one of the trunnion pins in each of the pillow blockpin receptive bores, to carry out general disposition of the trunnion at810.

An integral flanged wear sleeve (265), such as described above, isinserted into each of the pillow block trunnion pin receptive bores(405, 410), over each respective trunnion drive pin (310) disposedtherein, at 815. This rotatably retains the respective trunnion drivepins, and thereby the trunnion (210), with respect to the respectivepillow block trunnion pin receptive bore, and hence the pillow blocks(230, 235). Additionally, or alternatively, mounting each of the pillowblocks, stacked one upon the other, at 805 may capture the flanged wearsleeves, on a trunnion pin, in each of the pillow block pin receptivebores.

At 820, a drive coupling (215, a “first” structure) is installed overthe trunnion (210), disposing other radial drive pins (310) of thetrunnion (210) in opposing drive coupling trunnion pin receptive bores(505).

Integral flanged wear sleeves (265), such as described above, areinserted into each of the drive coupling pin receptive bores (505), overa trunnion drive pin (310) disposed therein at 825. This rotatablyretains the respective trunnion drive pin with respect to the respectivedrive coupling trunnion pin receptive bore, and thus rotatably retainingthe trunnion (210) with respect to the drive coupling (215).

Thereafter, and/or 815 and/or 825, the installed flanged wear sleevesare secured, such as by a fastener, such as a bolt, being secured in(e.g. threaded into and tighten) each trunnion drive pin longitudinal(threaded) bore 315. Thusly, the fastener bears on, and tensionsagainst, the respective wear sleeve flange (270) to thereby replaceablyretain the respective wear sleeve (265) on the respective trunnion drivepin (310) and replaceably retain the flanged wear sleeve and trunnion(210) in place.

At 820, or thereafter, a splined central driveshaft/mast coupling bore(220) centrally defined by the drive coupling (215) is mated with arotor driveshaft/mast of an aircraft to operatively mount the gimbaledrotor hub (200). Tilting of the gimbaled rotor hub on thedriveshaft/mast and tilting of proprotors secured to the proprotor yokeis allowed by the proprotor yoke central driveshaft/mast opening (290)being larger than the annular body central driveshaft/mast opening(305), and the annular body central driveshaft/mast opening being largerthan the drive coupling splined opening (220) (and hence larger that theaircraft driveshaft/mast).

Various ones of the above steps may be performed in one or otherprogressions. For example, the trunnion (210) may be deployed first,then the pillow blocks (230, 235) may be mounted around the pins (310).In such an implementation, the drive coupling (215) may be assembled onthe trunnion, then the pillow blocks may be assembled around theremaining trunnion pins.

Removal and replacement of a flanged wear sleeve (265) may be carriedout at 830 through 840, as required. At 830 a fastener (bolt 285)securing a flanged wear sleeve to be replaced is removed (e.g. screwedout of respective trunnion pin bore 315). The wear sleeve to be replacedis removed (pulled out of bore 405, 410 or 505) at 835, with theremaining components of the gimballed rotor hub (200) remaining inplace. That is, at 835, the wear sleeve to be replaced is removedwithout removal of the rotor hub gimbal, any of the other wear sleeves,or any other components of the gimballed rotor hub. At 840, therespective wear sleeve is replaced by inserting a new integral flangedwear sleeve in the respective pin receptive opening (405, 410, 505) onthe respective trunnion pin 310, as in 815 or 825 above, and securingthe wear sleeve with a (threaded) fastener (such as by tightening thefastener into threaded bore 315 of the trunnion pin) as in 835, above.Thereby, replacement of a wear sleeve used in the present systems andmethods may be accomplished, with the remaining components of the rotorhub in place, that is, without removal of the rotor hub gimbal or anyother components thereof.

In a rotorcraft, or other aircraft with propeller pitch control, or thelike, a swashplate may translate flight control input into motion ofblades 115, or the like. Because blades 115 are typically spinning whenthe rotorcraft is in flight, the swashplate may, transmit flight controlinput from the non-rotating fuselage to hub 200, proprotor yoke 240,blades 115, and/or components coupling hub 200 to blades 115. To thisend, such a swashplate may be operatively coupled to proprotor yoke 240,or the like by a plurality of pitch links. This coupling between a pitchlink and a proprotor yoke may also include, but are not limited to,couplings between a pitch link and a blade or components coupling theproprotor yoke to blades 115. In various embodiments, a swashplateassembly may include a non-rotating swashplate ring and a rotatingswashplate ring. Non-rotating swashplate ring does not rotate with therotorcraft driveshaft or mast, whereas rotating swashplate ring doesrotate with the driveshaft or mast. In such embodiments, the pitch linksconnect rotating swashplate ring to blades 115, such as via proprotoryoke 240.

In operation, according to one example embodiment, translating thenon-rotating swashplate ring along an axis of the driveshaft or mastcauses the pitch links to move up or down. This changes the pitch angleof all of blades 115 equally, increasing or decreasing the thrust of therotor, and in the case of a helicopter or tiltrotor craft 100 inhelicopter mode, causing the aircraft to ascend or descend. Tilting thenon-rotating swashplate ring causes the rotating swashplate to tilt,moving the pitch links up and down cyclically as they rotate with thedriveshaft or mast. This tilts the thrust vector of the rotor, causingrotorcraft 100 to translate horizontally following the direction theswashplate is tilted. To facilitate such tilting of the rotatingswashplate, it may be gimbaled, similar to hub 200.

As noted, the present systems and methods are described above withreference to a rotorcraft rotor (proprotor) hub. However, variousembodiments of the present systems and methods are applicable to notonly aircraft rotor or propeller hub assemblies, but also to swashplateassemblies to gimbal a rotating swashplate, or the like, facilitatingtilting of the rotating swashplate, as well as movement of the rotatingswashplate along the driveshaft or mast. For example, in a swashplateimplementation, or the like, a first structure may be splined to a mastor driveshaft of a proprotor aircraft for movement along the mast ordriveshaft, perpendicular to the aforementioned single plane. A secondstructure and/or third structure (e.g. making up the rotating swashplatering) may be adapted to rotate in the single plane and tilt relative tothe single plane, about first and second (respective axes), parallel tothe single plane and may be linked to proprotors of the aircraft and thenon-rotating ring.

Hence, although the present invention and its advantages have beendescribed in detail, it should be understood that various changes,substitutions and alterations can be made herein without departing fromthe spirit and scope of the invention as defined by the appended claims.Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure of the present invention, processes,machines, manufacture, compositions of matter, means, methods, or steps,presently existing or later to be developed that perform substantiallythe same function or achieve substantially the same result as thecorresponding embodiments described herein may be utilized according tothe present invention. Accordingly, the appended claims are intended toinclude within their scope such processes, machines, manufacture,compositions of matter, means, methods, or steps.

What is claimed is:
 1. A gimbal joint comprising: a first plurality ofintegral flanged wear sleeves, each integral flanged wear sleevedisposed between a pin or pin receptive bore of an integral trunnion anda corresponding pin receptive bore or pin of an integral coupling, theintegral trunnion coupled to a mast or driveshaft of an aircraft formovement along the mast or driveshaft and adapted to rotate in a singleplane and the integral coupling adapted to move along the mast ordriveshaft, rotate in the single plane and tilt relative to the singleplane about a first axis parallel to the single plane; a secondplurality of integral flanged wear sleeves, each disposed betweenanother pin or pin receptive bore of the integral trunnion and acorresponding pin receptive bore or pin of a pillow or mounting block,the block adapted to rotate in the single plane and tilt relative to thesingle plane about a second axis parallel to the single plane andperpendicular to the first axis; each integral flanged wear sleevecomprising: a right circular hollow cylindrical body portion interiorlysized to be retained on one of the pins and externally sized to beretained in one of the pin receptive bores; and a flange portionradiating from an outer end of the cylindrical body portion, the flangeportion having a diameter larger than a diameter of the pin receptivebores and bearing on a face of a respective structure.
 2. The gimbal ofclaim 16, wherein at least one of the flanged wear sleeves furthercomprises: a low friction coating or lining disposed on at least anouter surface of the body portion; a low friction coating or liningdisposed on an inner surface of the body portion of the at least oneflanged wear sleeve; and/or a low friction coating or lining disposed onan inner face of a flange portion of the at least one flanged wearsleeve.
 3. The gimbal joint of claim 1, wherein each pin furthercomprises a longitudinal bore, and the gimbal joint further comprises afastener secured in each longitudinal bore, bearing on, and tensionedagainst, the respective wear sleeve flange, replaceably retaining therespective wear sleeve on the respective pin and in the respective pinreceptive bore.
 4. The gimbal joint of claim 1, wherein the rightcircular hollow cylindrical body portion is interiorly sized to beretained on one of the pins and externally sized to be rotatablyretained in one of the pin receptive bores.
 5. The gimbal joint of claim1, wherein the right circular hollow cylindrical body portion isinteriorly sized to be retained on one of the pins and externally sizedto be retained in one of the pin receptive bores.
 6. The gimbal joint ofclaim 1, wherein the integral trunnion defines opposing integraltrunnion pin portions and an integral internally splined centraldriveshaft or mast coupling bore portion configured to mate with a rotordriveshaft or mast end and spline the integral trunnion to the mast ordriveshaft for movement along the mast or driveshaft, perpendicular tothe single plane.
 7. The gimbal joint of claim 6, wherein: the integralcoupling is ring-shaped, defines integral pin receptive bore portionsconfigured for rotatably pinning to the integral trunnion via thetrunnion pins, and defines integral coupling pin portions; the pillow ormounting block comprises a plurality of pillow blocks, each pillow blockdefining a coupling pin receptive bore and secured to, or an integralpart of, a rotor yoke of the aircraft; and one of each of the first orsecond plurality of integral flanged wear sleeves is disposed in eachcoupling ring pin receptive bores and in each pillow block pin receptivebore, over respective trunnion drive pins or coupling ring drive pins,rotatably retaining the respective trunnion drive pin with respect tothe respective coupling ring pin receptive bore, or the respectivecoupling ring drive pin with respect to the respective pillow block pinreceptive bore, coupling the integral trunnion to the rotor yoke of theaircraft.
 8. The gimbal joint of claim 6, wherein: the pillow ormounting block comprises a plurality of mounting blocks, each mountingblock defining a mounting pin and secured to, or an integral part of, arotor yoke of the aircraft; the integral coupling is a ring-shapedintegral ring coupling and defines a plurality of integral pin receptivebore portions configured for rotatably pinning to the integral trunnionvia the trunnion pins and rotatably pinning to the mounting blocks viarespective mounting pins; and one of each of the first or secondplurality of integral flanged wear sleeves is disposed in each integralring coupling pin receptive bores over a respective trunnion drive pinor mounting block pins, rotatably retaining the respective trunniondrive pin or mounting block pin with respect to the respective integralring coupling pin receptive bore, coupling the integral trunnion to themounting blocks and thereby to a rotor yoke of the aircraft.
 9. Anaircraft gimbal comprising: an integral trunnion comprising: an annularbody portion defining a central splined central driveshaft or mastcoupling bore configured to mate with a rotor driveshaft or mast end;and a plurality of drive pin portions extending from the annular bodyportion; a pair of blocks configured to be secured to, or is an integralpart of, a rotor yoke; an integral coupling defining: opposing trunnionpin receptive bores; and a plurality of integral flanged wear sleeves,one integral flanged wear sleeve disposed in each of the integralcoupling trunnion pin receptive bores, over a respective trunnion drivepin, rotatably retaining the respective trunnion drive pin with respectto the respective integral coupling trunnion pin receptive bore, eachintegral flanged wear sleeve comprising: a right circular hollowcylindrical body portion interiorly sized to be retained on one of thetrunnion drive pin portions of the trunnion and externally sized to berotatably retained in one of the pillow block trunnion pin receptivebores and/or one of the drive coupling trunnion pin receptive bores; anda flange portion radiating from an outer end of the cylindrical bodyportion, the flange portion having a diameter larger than a diameter ofthe pillow block trunnion pin receptive bores and the drive couplingtrunnion pin receptive bores, bearing on a face of a respective pillowblock or a respective face of the drive coupling.
 10. The gimbal ofclaim 9, wherein at least one of the flanged wear sleeves furthercomprise: a low friction coating or lining disposed on at least an outersurface of the body portion; a low friction coating or lining disposedon an inner surface of the body portion of the at least one flanged wearsleeve; and/or a low friction coating or lining disposed on an innerface of a flange portion of the at least one flanged wear sleeve. 11.The gimbal of claim 9, wherein each drive pin portion of the integraltrunnion further comprises a longitudinal bore, and the rotor hub gimbalfurther comprises a fastener secured in each trunnion drive pinlongitudinal bore and bearing on, and tensioned against, the respectivewear sleeve flange, replaceably retaining the respective wear sleeve onthe respective integral trunnion drive pin and replaceably retaining theflanged wear sleeve and integral trunnion in place.
 12. The gimbal jointof claim 9, wherein the integral trunnion drive pin portions areopposing integral trunnion pin portions and the central splined centraldriveshaft or mast coupling bore is further configured to spline theintegral trunnion to the mast or driveshaft for movement along the mastor driveshaft.
 13. The gimbal joint of claim 12, wherein: the integralcoupling is ring-shaped and further defines integral coupling pinportions; the blocks are pillow blocks, each pillow block defining acoupling pin receptive bore; and one integral flanged wear sleeves isdisposed in each pillow block pin receptive bore, over respectiveintegral coupling ring drive pins, rotatably retaining the respectivecoupling ring drive pin with respect to the respective pillow block pinreceptive bore, coupling the integral trunnion to the rotor yoke. 14.The gimbal joint of claim 12, wherein: the blocks are mounting blocks,each mounting block defining a mounting pin; the integral coupling is aring-shaped integral ring coupling and the pin receptive bore portionsare configured for rotatably pinning to the integral trunnion via thetrunnion pins and rotatably pinning to the mounting blocks viarespective mounting pins; and integral flanged wear sleeves are disposedin integral ring coupling pin receptive bores over respective mountingblock pins, rotatably retaining the respective mounting block pin withrespect to the respective integral ring coupling pin receptive bore,coupling the integral trunnion to the mounting blocks and thereby to therotor yoke.
 15. A proprotor gimbal, comprising: a yoke configured formounting a plurality of proprotors thereto; a pair of blocks attached tothe yoke; an integral coupling having a pair of opposed bores, each witha flanged wear sleeve, the integral coupling rotatably pinned to thepair of blocks; and, an integral trunnion comprising an annular bodydefining a splined mast opening configured to mate with a rotor mast anddefining a pair of opposed trunnion pins extending outwardly from theannular body, each trunnion pin extending into one of the flanged wearsleeves in the integral coupling opposed bores; and, each flanged wearsleeve comprising a right circular hollow cylindrical body portioninteriorly sized to be retained on one of the trunnion pins andexternally sized to be rotatably retained in one of the integralcoupling opposed bores.
 16. The proprotor gimbal of claim 15, wherein atleast one of the flanged wear sleeves further comprises: a low frictioncoating or lining disposed on at least an outer surface of the bodyportion; a low friction coating or lining disposed on an inner surfaceof the body portion of the at least one flanged wear sleeve; and/or alow friction coating or lining disposed on an inner face of a flangeportion of the at least one flanged wear sleeve.
 17. The proprotorgimbal of claim 15 wherein the integral trunnion splined mast opening isfurther configured to spline the integral trunnion to the mast ordriveshaft for movement along the mast or driveshaft.
 18. The proprotorgimbal of claim 15, wherein: the integral coupling is ring-shaped,defines integral pin receptive bore portions configured for rotatablypinning to the integral trunnion via the trunnion pins, and definesintegral coupling pin portions; the blocks are pillow blocks and eachpillow block defines a coupling pin receptive bore; and one of theflanged wear sleeves is disposed in each coupling ring pin receptivebore and in each pillow block pin receptive bore, over a respectivetrunnion drive pin or coupling ring drive pin, rotatably retaining therespective trunnion drive pin with respect to the respective couplingring pin receptive bore, or the respective coupling ring drive pin withrespect to the respective pillow block pin receptive bore, coupling theintegral trunnion to the yoke.
 19. The proprotor gimbal of claim 15,wherein: the blocks are mounting blocks, each mounting block defining amounting pin; the integral coupling is a ring-shaped integral ringcoupling and defines a plurality of integral pin receptive bore portionsconfigured for rotatably pinning to the integral trunnion via thetrunnion pins and rotatably pinning to the mounting blocks viarespective mounting pins; and one of the flanged wear sleeves isdisposed in each integral ring coupling pin receptive bore over arespective trunnion drive pin or mounting block pin, rotatably retainingthe respective trunnion drive pin or mounting block pin with respect tothe respective integral ring coupling pin receptive bore, coupling theintegral trunnion to the mounting blocks and thereby to the yoke. 20.The proprotor gimbal of claim 15, wherein each pin further comprises alongitudinal bore; and the proprotor gimbal further comprises a fastenersecured in each pin longitudinal bore, the fastener bearing on, andtensioned against, a respective flange portion of each flanged wearsleeve, replaceably retaining the respective flanged wear sleeve on therespective pin.